Is there a way to restrict discounts from applying on select SKUs?

When creating a promotion or coupon, you can set up the Coupon Applies To section to only discounts select Collection.

We will use the Collection feature to restrict discounts from applying to certain SKU. We'll do so by creating a Collection called “Discountable SKUs” and add all the SKUs you want to discount to that one collection. Then when you create a promotion or coupon, make it only available to the 'Discountable SKUs' collection.